The present invention generally relates to remote analysis of analytes and more particularly remote analysis of analytes present in the vapor or odor phase of a sample.
There is considerable interest in developing sensors that act as analogs of the mammalian olfactory system (Lundstrom et al., Nature 352:47-50, 1991; Shurmer and Gardner, Sens. Act. B 8:1-11, 1992; Shurmer and Gardner, Sens. Actuators B 15:32, 1993). Such sensors have proven useful in the detection of small molecules and odorants.
Such broadly responsive sensor arrays have exploited heated metal oxide thin film resistors (Gardner et al., Sens. Act. B4:117-121, 1991; Gardner et al., Sens. Act. B 6:71-75, 1991), polymer sorption layers on the surfaces of acoustic wave resonators(Grate and Abraham, Sens. Act. B 3:85-111, 1991; Grate et al., Anal. Chem. 65:1868-1881, 1993), arrays of electrochemical detectors (Stetter et al., Anal. Chem. 58:860-866, 1986; Stetter et al., Sens. Act. B 1:43-47, 1990; Stetter et al., Anal. Chem. Acta 284:1-11, 1993), conductive polymers or composites that consist of regions of conductors and regions of insulating organic materials (Pearce et al., Analyst 118:371-377, 1993; Shurmer et al., Sens. Act. B 4:29-33, 1991; Doleman et al., Anal. Chem. 70:2560-2654, 1998; Lonergan et al., Chem. Mater. 8:2298, 1996). Arrays of metal oxide thin film resistors, typically based on tin oxide (SnO2) films that have been coated with various catalysts, yield distinct, diagnostic responses for several vapors (Corcoran et al., Sens. Act. B 15:32-37, 1993). Surface acoustic wave resonators are sensitive to both mass and acoustic impedance changes of the coatings in array elements, but the signal transduction mechanism involves somewhat complicated electronics, requiring frequency measurement to 1 Hz while sustaining a 100 MHZ Rayleigh wave in the crystal. Attempts have also been made to construct arrays of sensors with conducting organic polymer elements that have been grown electrochemically through use of nominally identical polymer films and coatings. Moreover, Pearce et al., Analyst 118:371-377, 1993; and Gardner et al., Sensors and Actuators B 18-19:240-243, 1994, describe, polypyrrole based sensor arrays for monitoring beer flavor. Shurmer (1990) U.S. Pat. No. 4,907,441, describes general sensor arrays with particular electrical circuitry. U.S. Pat. No. 4,674,320 describes a single chemoresistive sensor having a semi-conductive material selected from the group consisting of phthalocyanine, halogenated phthalocyanine and sulfonated phthalocyanine, which was used to detect a gas contaminant. Other gas sensors have been described by Dogan et al., Synth. Met. 60:27-30, 1993; and Kukla, et al. Films. Sens. Act. B., Chemical 37:135-140, 1996.
Measurement of air content for the detection of contaminants has become a growing concern both in the workplace (e.g., factories and laboratories), as well as in residential neighborhoods and homes. Currently, detection of hazardous chemicals or air contaminants is the result of reactions by humans and animals which are sensitive to the analyte. Upon detection, hazardous chemical teams or air-quality specialists are mobilized to the area of contamination with specialized equipment for collecting the analyte. The readings are then collected manually and often the sample is then physically taken to a separate location for analysis. These current methods require hazardous materials teams to physically enter the area and submit themselves to risks associated with the hazard.
In addition, breath testing has long been recognized as a non-intrusive medical technique that allows for diagnosis of disease or the presence of analytes. Medical symptoms of many types of conditions can be difficult to detect by medical professionals or their detection requires costly, time consuming, and highly invasive procedures often resulting in lost man hours at work, and increased risks of mortality and morbidity. Currently, medical diagnostics such as blood pressure readings and glucose readings are taken at doctors"" offices or blood laboratories. The readings are then collected manually and depend on the patient""s state of health at that particular time. In some cases, individuals take readings at home to assist doctors to better determine medication identification and levels. This data depends on the patient""s proficiency and accuracy at taking readings, and is hard for the physician to analyze and is normally communicated only at a doctor""s visit. Typically, the patient is diagnosed and medicated based on a minimum amount of data and analysis, which furthermore is not presented to the doctor in a format that facilitates diagnosis. Each reading is presented by an individual manually listing out his own readings with the date and time that these readings are takenxe2x80x94often in irregular intervals.
Diagnosis of many types of medical conditions, such as hypoglycemia and diabetes mellitus, can be markedly improved by a system to consolidate the data and present the data in a format which facilitates such diagnosis. In addition, remote monitoring of chemical hazard reduces the risk associated with local detection.
The present invention provides compositions and systems useful in remote monitoring of chemical hazards, air quality, and medical conditions, for example, robotic systems to search for and detect explosives, mines, and hazardous chemicals. In addition, the methods, systems and compositions of the invention provide the ability to mine data from a database containing a plurality of chemical fingerprints.
Accordingly, in one embodiment, the present invention is used with subjects who may have a medical condition such as, for example, diabetes mellitus to improve diagnosis and treatment of medical disorders more accurately and to assist medical practitioners in determining the proper amount of medication or other treatment to prescribe. The term xe2x80x9cmedical practitionerxe2x80x9d is intended to include any individual who treats, or prescribes treatment to another individual to improve the latter""s health or well-being. One embodiment of the invention is to gather, organize, and present data which may be collected over a long period of time in a way that best facilitates accurate diagnosis and proper treatment of such medical conditions which can require long-term profiling of medical readings.
In one embodiment, a method for remote characterization of a gaseous or vapor sample is provided. The method includes contacting at least one sensor with a gaseous or vapor sample, wherein the sample contains at least one analyte, the sensor providing a detectable signal when contacted by the analyte, transmitting data corresponding to the detectable signal to a remote location, analyzing the data received at the remote location, and identifying the analyte present in the gaseous or vapor sample thereby characterizing the sample.
In another embodiment, the invention provides a sensor array system f6r remote characterization of a gaseous or vapor sample. The system includes at least one sensor, wherein the sensor provides a detectable signal when contacted by an analyte; a measuring apparatus, in communication with the sensor capable of measuring the detectable signal; a transmitting device, in communication with the measuring apparatus for transmitting information corresponding to the detectable signal to a remote location; and a computer comprising a resident algorithm capable of characterizing the analyte.
In yet another embodiment, the invention provides a method for remote characterization of a disease in a subject. The method includes contacting at least one sensor with a gaseous or vapor sample obtained from the subject, wherein the sensor provides a detectable signal when contacted by an analyte present in the sample. In one embodiment the sensor has regions of a conductive material and regions of a material compositionally different than the conductive material, and wherein the materials provide an electrical path through the regions of conductive material and compositionally different material of the sensor, wherein interaction of the analyte with the sensor changes the resistance of the sensor. Electrically measuring the change in resistance as a detectable signal of the sensor, transmitting data corresponding to the detectable signal to a remote location; analyzing the data received at the remote location; and identifying the analyte present in the gaseous or vapor sample thereby characterizing the disease.
In yet another embodiment, the invention provides a method of monitoring trends across populations or changes in a physical state of a subject over a period of time. The method includes contacting at least one sensor with a gaseous or vapor sample obtained from the subject at two or more time points, wherein the sensor provides a detectable signal when contacted by an analyte present in the sample, transmitting data corresponding to the detectable signal to a remote location; analyzing the data received at the remote location; and identifying a change in an analyte present in the gaseous or vapor sample.